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Re: Disjunction vs. Optional ... and UNION

From: Arjohn Kampman <arjohn.kampman@aduna.biz>
Date: Wed, 23 Mar 2005 11:21:06 +0100
Message-ID: <42414312.2040607@aduna.biz>
To: Bob MacGregor <bmacgregor@siderean.com>
Cc: public-rdf-dawg-comments@w3.org

Bob MacGregor wrote:
[...]
>> The query
>>
>> SELECT ?x ?y
>>   WHERE  { ?book dc10:title ?x }
>>
>> can return bindings - it's a projection of a query solutions involving 
>> ?x and ?book.
>>
> This is a horrendous decision by the committee.  The above query ought 
> to be flagged as illegal.
[...]

If the above is true, then I fully agree with you here. The variable ?y
is never mentioned in any triple pattern, so why would one be interested
in it? It is far more likely that this is a typo made by the developer,
and it should be treated as such. Not doing so will make SW applications
unnecessarily difficult to debug.

Regards,

Arjohn

-- 
arjohn.kampman@aduna.biz
Aduna BV - http://aduna.biz/
Prinses Julianaplein 14-b, 3817 CS Amersfoort, The Netherlands
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Received on Wednesday, 23 March 2005 10:21:09 GMT

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